A pin grid array (PGA) version, used in the high-end Macintosh Quadra line.
The Motorola 68040, also referred to as the 68040 or '040, is a 32-bit CISC processor that was produced by Motorola's Semiconductor Products Sector, superseding the Motorola 68030. The 68040 was used in the Centris, Quadra, and PowerBook 500 series. It was also used in the NeXTcube and NeXTstation computers. It was the last of the 68k processor series to be used by Apple Computer, which migrated to PowerPC processors for its Power Macintosh line.
Features[]
A quad flat package (QFP) version, used in the PowerBook 500 series.
Introduced in 1990, the 68040 improved processor performance over the 68030 by increasing the instruction and data caches eight-fold to 4 kilobytes each. Instruction pipelining was doubled to 6 stages.[1] However, the pipelined cache was known to break some older hard-coded software. This could be turned off with a software cache switch for the sake of backward compatibility, but at the expense of a 3-fold penalty in performance.[2][3]
Internal units operated at twice the speed of the external clock, so Apple and other companies sometimes marketed their 68040-based products with two clock speeds, such as 66/33MHz.[1][4]
The 68040 was available in external clock speeds up to 40MHz in a ceramic pin grid array (PGA) package. However, heat became a factor in the design and a 50MHz version was cancelled. The compact quad flat package (QFP) version was delayed for Apple's PowerBook 500 series and limited to 33MHz.
Variants[]
- Motorola 68LC040 - a low-cost version without a built-in floating-point unit.[5] Mostly used in entry-level and portable Macintosh models. Units with mask numbers lower than 03E23G (manufactured before late 1994) contain a bug which breaks software emulating a floating-point unit, such as SoftwareFPU. These defective units were found in many early Macintosh LC 475s and Quadra 605s. Patrick Fleming of Apple Computer reportedly denied the existence of the bug, but Motorola confirmed it as bug E4 in revision 4 of their official 68LC040 errata sheet.[6][7]
- Motorola 68EC040 - a lower-cost embedded version without built-in floating-point nor memory management units. Not used by Apple in any model.
Macintosh models with 68040 processors[]
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68040 pin grid array (PGA) version: (with FPU)
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68LC040 pin grid array (PGA) version: (no FPU)
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68040 Quad flat package (QFP) version: (with FPU)
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68LC040 Quad flat package (QFP) version: (no FPU)
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References[]
- ↑ 1.0 1.1 68040 Microprocessor, LogicOnline. Archived 1999-04-21.
- ↑ A Pipelined CISC Processor: the 68040 by Leslie S. Smith. 2004.
- ↑ Cache is King – Enable Yours, HappyMacs. 2013-06-28.
- ↑ Frequently Asked Questions, MicroMac. 1998-05-16.
- ↑ Technote 1011: Understanding Type 11 & No FPU Installed Errors on the Power Macintosh by Brian Bechtel, Apple Computer. 1995-10. Archived 1997-06-15.
- ↑ Will Apple replace 68LC040s with CPU bug? by Daniel Hird, Google Groups. 1994-08-22.
- ↑ 605 & Floating Point Error by Robin Macrae, Google Groups. 1994-11-18.
See also[]
- Cache Switch control panel, for managing 68040 instruction and data caches.
External links[]
- Motorola 68040 microprocessor family at CPU-World
- 68040 class ICs at CPU-Collection.de
- Motorola 68040 Macs at ForeverMac (archived 2014-09-13, 2011-10-06)
- Motorola 68LC040 Macs (archived 2014-08-14, 2011-10-06)
- 68LC040 CPU Bug Information at John Neil & Associates (PDF, 1999-01-30)
- CPUs: Motorola 68040 at Low End Mac (2014-06-14)
- Options for '040s by Adam Robert Guha (2000-06-05)
- MC68040: (Including EC, LC, and V) at NXP
- Motorola 68040 at Wikimedia Commons
- Motorola 68040 and Motorola 68000 series at Wikipedia
